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interview

LTE in the Land of the Rising Sun

As part of our look at the Japanese LTE market and ahead of his speaking appearance at the sixth annual LTE Asia conference, we speak to Sadayuki Abeta, director of the Radio Access Network development, for leading Japanese mobile operator NTT DoCoMo.

As the LTE dawn breaks, it’s no surprise to find that the Land of the Rising Sun is one of the first places to host a live LTE deployment. And at the forefront of LTE in Japan is NTT DoCoMo, incumbent operator and habitual pioneer.

NTT DoCoMo is Japan’s leading network operator, with over 58 million customers and more than 48 per cent of the local market at the end of the first quarter of 2011, according to Informa WCIS stats. The network has a long history of leadership in mobile data services and first gained worldwide attention for the i-Mode technology it introduced in 1999, which became a major domestic success.

The consumer enthusiasm generated by i-Mode was in marked contrast to the fortunes of the WAP service favoured in Europe. It then gained further fame in 2001 when it launched the world’s first W-CDMA network, under the FOMA brand. And while NTT DoComo may not have been the very first off the starting block with LTE, it was certainly among the leading pack – its service went live on December 24th 2010.

For a country generally associated with leading edge technology it would be unusual if NTT DoCoMo were the only operator to be looking at LTE. Indeed, second placed KDDI has committed itself to LTE, and has 20MHz of spectrum in which to deploy the technology. An LTE trial using 1.5GHz spectrum took place in the Nasu-Shiobara area (Tochigi Prefecture) between March and August 2010 and an urban field trial began in October 2010. KDDI said that it plans to launch LTE in December 2012 and has committed to 96.5 per cent coverage by March 2015.

While third placed operator Softbank has yet to announce trials or release dates for LTE, it has joined the Global TD-LTE Initiative, along with China Mobile and Bharti Airtel. This is a consortium aimed at raising the profile of the TDD flavour of LTE technology with the intention of growing its eco-system. Finally, eMobile also plans to launch LTE as a follow-up to its Dual Carrier HSPA+ network.

Amongst all of those however, NTT DoCoMo is the only one that can boast a live network. The service currently takes in the major cities of Toyko, Nagoya and Osaka, and operates in the 2.1GHz frequency commonly used worldwide for 3G. In most areas it is using 5MHz of FDD bandwidth, which it says is enough to give it a theoretical speed on the downlink of 37.5Mbps and 12.5Mbps of uplink. In indoor areas, such as Tokyo airport, it is using 10MHz of bandwidth, which doubles that throughput to a theoretical 75Mbps on the downlink and 25Mbps of uplink.

NTT DoCoMo wants eventually to fully re-farm its 2.1GHz from 3G to LTE. To do this, it plans to shut down its 2G network in 2012, and use the freed-up 800MHz frequencies, which have better propagation characteristics, for its 3G service.

As one of the few operators to select 2.1GHz for LTE, NTT DoCoMo is eager to expand the eco-system. At the LTE World Summit in Amsterdam in May, Seizo Onoe, the company’s managing director of R&D strategy called on the industry to support 2.1GHz for LTE— comments that NTT DoCoMo’s director of the Radio Access Network development, Sadayuki Abeta, reiterates to Telecoms.com. “For 2.1GHz we have experience—so we can share this experience with other operators if they have an interest.”

Abeta also points towards the reduced cost of deployment as a reason to stay with 2.1GHz. Base stations in much of its W-CDMA network are equipped with dual W-CDMA/LTE remote radio equipment and these can be easily upgraded for LTE with the addition of an LTE BDE (base station digital equipment). “Many parts of 3G and LTE [technologies] we use are common,” Abeta says. “For example the radio remote equipment overhead we can share between LTE and 3G, so the migration is cheap.”

As with all deployments outside of the US, NTT DoComo is initially supporting only USB dongles and Mi-Fi hotspot devices, but plans to add LTE tablets and smartphones as soon as possible. Abeta, does not say exactly which models these will be but says that several vendors will be involved.

While VoLTE remains on the discussion agenda, DoCoMo will be relying on Circuit Switch (CS) fallback for voice, when it launches LTE smartphones. Abeta explains that, before the carrier can adopt VoLTE, it is vital to ensure that Japan’s automated earthquake warning system, which sends a mass text message as soon an earthquake is detected, works flawlessly.

However, he emphasises that VoLTE was very much on the carrier’s to-do list. “We are planning to support VoLTE in the future, but we haven’t decided yet when we will introduce this. Maybe when the vendors can support both [VoLTE and CS fallback]. 2013-14 is our target.”

For its LTE launch NTT DoCoMo has selected the brand name ‘Xi’—pronounced ‘Crossy’. This is an intriguing decision in terms of marketing as it mentions neither the acronym LTE nor the term ‘4G’ so adored in the North American and Canadian markets. Abeta’s explanation for this is simply that, according to the 3GPP, LTE is considered 3.9G and that only IMT Advanced qualifies as true 4G. It’s a refreshingly technical approach to technology nomenclature and speaks volumes about NTT DoCoMo’s confidence in the technical savviness of the Japanese consumer. “For the Japanese market, I don’t think customers are confused,” says Abeta. “I think they know that Xi is the brand name of LTE, so they are not confused”.

Most of DoCoMo’s current LTE customers are business users, Abeta acknowledges, who are the first to develop a need for higher speeds. However, he does not share the real-world throughput of the network as it compares to theoretical peak rates. “It depends on the area and the number of customers,” he says. “It’s difficult to say so we don’t quote average throughput. We haven’t announced any official figures at this moment.”

However, with the arrival of smartphones and greater coverage he expects LTE to rapidly become a mainstream proposition, but admits that the pace of that roll-out will be a challenge and depend on expected demand. “Our target is that most of the [country] is covered by 2014—[but] according to the number of customers maybe this will change.” Unlike some early movers NTT DoCoMo has no obligation to roll-out LTE to remote areas. But with near ubiquitous 3G coverage, and solid Dual Carrier HSPA in many places, Abeta says that this is not a major issue. “Where there are people we will support [LTE]. But maybe where there is a mountain area we will have 3G.”

What’s clear is that Abeta is certain that moving first to LTE has given NTT DoCoMo a tangible competitive advantage. “Other operators in Japan will support LTE next year- maybe. So by introducing LTE [now] we believe that we have an advantage. And as there are already LTE terminals we didn’t have to wait.”

One comment

whats the time frame for refarming the 2100 band to LTE? and obviously at some point all of 3g will be refarmed to LTE- including the 800 band and the rural towers because LTE is supposed to be more cost effective for data and most efficient in spectrum use – no? is there a time frame on that?

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